JPH0443790A - Reproducing video signal processing unit - Google Patents

Abstract

PURPOSE:To facilitate the reproduction of a sharp video image while color masking is hardly caused by inserting a pseudo color subcarrier signal to a position equivalent to a color burst signal of a reproduced video signal without a color burst signal. CONSTITUTION:A pseudo color subcarrier signal insertion circuit 9 consists of an analog switch circuit and uses a pulse signal from a pulse signal generating circuit 7 as a timing signal to output switchingly a white black video signal for a period other than a pulse period and a pseudo color subcarrier signal from a pseudo color subcarrier signal generating circuit 11 for the pulse period switchingly. Then a color subcarrier signal is inserted and outputted to a reproduced video signal not including a color burst signal for a period equivalent to a color burst signal of the color television signal. Thus, an ACC (Automatic Color Control) circuit of a color signal processing circuit at a post-stage hardly malfunctions and the color video display device reproduces a sharp video image in which color mask hardly takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reproduced video signal processing device, and particularly to a reproduced video signal processing device suitable for displaying a reproduced monochrome video signal on a color video display device.

[Prior Art] As shown in FIG. 3, a video camera 1 reproduces images on a color image display device 5 such as a color CRT display connected to a video tape recorder (hereinafter abbreviated as VTR) 3. Common.

[Problem to be Solved by the Invention] However, when the video camera 1 outputs a black and white video signal, the VTR 3 and the color video display device 5 generally have a circuit configuration that handles color television signals. Therefore, noise having the same frequency component as the color burst signal may be added to the black and white video signal in the color burst portion of the VTR 3 or the color video display device 5.

In such a case, since the color image display device 5 detects the noise as a color burst signal, the color signal processing circuit operates from a black and white video signal as a color video signal, and for example, stripes appear on a color screen even though it is a black and white video. There is a risk that the pattern may become red or blue, or a yellow mask may appear.

The present invention has been made in order to solve these conventional drawbacks, and it is possible to reproduce a video signal from a VTR or the like without a color burst signal, such as a black and white video signal, on a color video display device. To provide a reproduced video signal processing device which is difficult to apply a color mask and can easily reproduce clear video.

[Means for Solving the Problems] In order to solve such problems, the present invention provides a pseudo color subcarrier signal generation circuit that outputs a pseudo color subcarrier signal having the same or similar frequency as a color burst signal, and a magnetic Pseudo color subcarrier signal insertion for inserting the pseudo color subcarrier signal at a position corresponding to the color burst signal portion of a playback video signal that is played back from a recorded state and does not have a color burst signal. It has a circuit and is configured to create a video signal to which a pseudo color subcarrier signal is added.

[Function] In the present invention equipped with such a means, a pseudo color subcarrier signal is inserted into a reproduced video signal that does not include a color burst signal in a period corresponding to the color burst signal of a color television signal, and is output. be done.

As a result, ACC (Au
This makes it difficult for the (column control) circuit to malfunction, and a color video display device reproduces video without a color mask.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a reproduced video signal processing device according to the present invention.

In the figure, the pulse signal generation circuit 7 is a pulse oscillation circuit that generates a pulse signal that is synchronized with the color burst signal period of the NTSC color television signal and has the same pulse width using a synchronization signal from the synchronization separation circuit 13, which will be described later. Yes, the horizontal synchronization signal H of the black and white video signal is shown in Figure 2.
It outputs a pulse signal P that rises after counting the same number as the count from the front end or rear end of the NTSC color television signal to the color burst signal of the NTSC color television signal, and is connected to the pseudo color subcarrier signal insertion circuit 9.

A pseudo color subcarrier signal generation circuit 11 is also connected to the pseudo color subcarrier signal insertion circuit 9.

This pseudo color subcarrier signal generation circuit 11 is
Frequency 3 of color burst signal of SC color television signal
．． 58MHz or a frequency close to this, e.g. 3.58M
It oscillates and outputs a pseudo color subcarrier signal of Hz or 4MHz.

As this pseudo color subcarrier signal, for example, a signal from a 3.58 MHz oscillation circuit built in the VTR 3 or a frequency-divided signal from a motor drive circuit may be used.

The pseudo color subcarrier signal insertion circuit 9 consists of an analog switch circuit to which a black and white video signal consisting of a synchronization signal H and a luminance signal Y is input, as shown in FIG. As a timing signal, the black and white video signal is switched and outputted during periods other than the pulse period, and a pseudo color subcarrier signal from the pseudo color subcarrier signal generation circuit 11 is switched and output during the pulse period.

That is, as shown in FIG. 2C, for a black and white video signal, N
A pseudo color subcarrier signal is inserted into a period corresponding to a color burst signal of a TSC color television signal.

The synchronization separation circuit 13 is a known circuit that separates the horizontal synchronization signal from the reproduced monochrome video signal and outputs it to the pulse signal generation circuit 7.

In the present invention configured in this manner, the pseudo color subcarrier signal B having the same frequency as the color burst signal of the color television signal is inserted into the back porch of the horizontal synchronizing signal H, so that the VTR 3 shown in FIG. When the reproduced video signal processing device of the present invention is provided in the front stage of the color video display device 5, the ACC circuit appropriately sets the gain of the video signal amplification circuit according to the pseudo color subcarrier signal level,
Color signals will be processed at a stable level.

Therefore, when there is no color burst signal as in the conventional example, noise with the same frequency component as the color burst signal is detected as the burst signal level, and the AC
The operation in which the C circuit sets the video signal amplification circuit to a large gain to amplify noise is suppressed, and this noise is no longer processed as a false color signal.

Therefore, the color video display device 5 reproduces a clear black and white video without applying a color mask.

In the present invention, since the operation of the color signal processing circuit is suppressed by the pseudo color subcarrier signal, selection of the frequency is important. frequency is selected.

Therefore, although it depends on the color television system, a frequency within 3.58 MHz to several hundred KHz is suitable for the NTSC color television signal.

Note that, in the present invention, if the signal is a black-and-white video signal or a digital signal input to the pseudo color subcarrier signal insertion circuit 9, the pulse signal generation circuit 7, the pseudo color subcarrier signal insertion circuit 9, and the pseudo color subcarrier signal generation circuit 11
It is also possible to configure it with a digital circuit.

[Effects of the Invention] As explained above, the present invention has a configuration in which a pseudo color subcarrier signal is inserted into a reproduced video signal without a color burst signal, for example, a reproduced monochrome video signal, in a period corresponding to a color burst portion. Therefore, the black-and-white video signal into which the pseudo-color subcarrier signal has been inserted is processed as a reproduced video signal with a color burst signal in the subsequent circuit, and even when the black-and-white video signal is reproduced on a color video display device, a color mask is applied. It is now possible to play back clear black and white images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the reproduced video signal processing device according to the present invention, FIG. 2 is a signal waveform diagram explaining the operation of the reproduced video signal processing device of FIG. 1, and FIG. 3 is a reproduced video 1 is a block diagram of a device used in a signal processing device; FIG. 1...Video camera, 3...Video tape recorder (VTR)
, 5... Color video display device, 7...
...Pulse signal generation circuit, 9...
・Pseudo color subcarrier signal insertion circuit, 11...
...Pseudo color subcarrier signal generation circuit 13
......Synchronization separation circuit.

Claims (1)

[Claims] (1) A pseudo color subcarrier signal generation circuit that outputs a pseudo color subcarrier signal with the same or similar frequency as a color burst signal, and a reproduced video signal that is reproduced from a magnetically recorded state and does not contain a color burst signal. a pseudo color subcarrier signal insertion circuit for inserting the pseudo color subcarrier signal into a reproduced video signal at a position corresponding to the color burst signal section, the video signal having the pseudo color subcarrier signal added thereto; A reproduction video signal processing device characterized in that: